


The Goop-Monster Effect

by Phlinting



Series: Slow Burn [4]
Category: Captain America - All Media Types, Marvel Cinematic Universe, The Avengers (Marvel Movies), The Avengers (Marvel) - All Media Types
Genre: Accidental MPREG in a non-MPREG world, Alternate Universe - Soulmates, F/M, M/M, Multi, Unplanned Pregnancy
Language: English
Status: Completed
Published: 2017-07-14
Updated: 2017-07-14
Packaged: 2018-12-01 22:43:27
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,368
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11496285
Author URL: https://archiveofourown.org/users/Phlinting/pseuds/Phlinting
Summary: When Darcy Lewis learned her soulmates were Steve Rogers and Bucky Barnes she'd known their life together would be far from normal. She hadn't, however, expected it to go quite like this…





	The Goop-Monster Effect

**Author's Note:**

> **This is the Mpreg version.**
> 
> The next part of this series is an alternate non-mpreg version of this story. Both versions fit into the following installments of the series so there is no need to read both (unless, of course, you really want to.)

_A couple of months ago..._

"Tough day at the office?" Darcy asked the moment Bucky and Steve finally made it back to their apartment. She wore a wry grin, so chances were she'd caught at least part of what had happened to them on the evening news. Somehow, no matter how often the Avengers saved New York, the TV crews always managed to get the most embarrassing shots of the fight or the aftermath. Even before they'd climbed into the quinjet pictures of their latest PR disaster had gone viral.

"Tough? You could say that," Steve said, reaching for Darcy and trying to pull her into a hug between them. She'd only just recovered from the alcohol poisoning aftermath of being kidnapped, so they'd both been in a hurry to get back home. But instead of sliding into her usual spot, Darcy danced away with an apologetic grimace.

"No offense to Tony's state-of-the-art decontamination showers, but you guys still really, _really_ stink."

"Seriously?" Bucky asked, tired enough to feel irrationally insulted by their soulmate's avoidance. "We still smell like goop monster?"

Darcy laughed at his phrasing but took another step back regardless. "Sorry, lover. The villain of the month is irrelevant. You still reek."

"Fine." Steve casually reached for Bucky's hand. "We're going to go scrub each other's backs," he said with a lecherous wink. "Don't wait up."

Darcy laughed happily and shooed them away. 

~*~

_Present day..._

"Don't forget the charity event tonight," Tony called, dutifully repeating the words their PR manager had very likely drummed into him every hour for the past three days.

"We won't," Steve called over his shoulder, not wanting to be distracted from his current, extremely important mission—getting Darcy and Bucky out of the building so the three of them could enjoy lunch in the park. It had been weeks since they'd been able to simply spend a few carefree hours in the sun all three of them together and Steve felt immeasurably sad for the loss. 

They should have been able to schedule more downtime for themselves, but with the Fantastic Four creating twice as many problems as they stopped—thanks to that horse's ass Reed Richards—and the X-men spending most of their time training the younger generation, it almost always fell to the Avengers to be the first line of defense. The only upside was that most attacks seemed to center on New York so most days they had a really short commute. 

But it was damned frustrating, especially when Steve wanted more time to spend with his soulmates. It didn't help his peace of mind at all that Darcy had shown an uncharacteristic inability to "bounce back" after the kidnapping attempt several months ago.

She'd quietly admitted to Bruce—who'd mentioned it to Steve not realizing he didn't already know—that it was not so much the kidnapping itself that was messing with Darcy's head, but rather Bucky's near breakdown afterward. Neither of them had realized that Darcy had been awake or coherent enough to understand Bucky's terrified words. Bucky would be horrified to realize he was responsible for Darcy's current overly cautious attitude. He knew better than most that everything could change drastically in a handful of moments, so Bucky would hate for Darcy to curb her enthusiasm for life simply because she was worried for him and how he'd react if she got hurt or died.

"Is it just me or is the pollution thicker than usual?" Bucky asked in a grumpy tone as they stepped out of the building and onto the sidewalk. Darcy wrinkled her nose and nodded in agreement.

"The air will be cleaner once we get there," Steve said, wrapping an arm around each of his lovers and turning them toward Central Park. He could understand Darcy's sensitive nose. She hadn't actually stepped out of the air-conditioned environment of Stark Tower in several weeks. She was bound to notice the difference. 

But Steve wasn't quite sure about Bucky's reason for making the observation. The pollution was no worse than it had been yesterday when they'd been fighting doombots on the Lower East Side. In fact without the charred and smoking ruins of downed Doombots it might even be a little better. For Bucky to mention it right now seemed important, but if it was Bucky's less than subtle way of getting them to abandon the idea of taking Darcy out in public he was going to be disappointed. Steve was strong enough to carry them both the entire way if he had to.

They were having a picnic, as a family, and all three of them were going to damn well enjoy it!

And yeah, okay, he'd check that attitude at the gate.

~*~

Some days Bucky hated the enhanced sense of smell that had come with everything else super-soldier serum related. The vehicle emissions had been difficult to ignore as they walked through the traffic, but the scent of the seasonal flowers growing along the edge of the park's entrance was even worse. Hell, he didn't even know what they were called, but he had the very real urge destroy every single one of them.

Fuck, that was awful. Who the hell had the idea to put such a strong scent where everyone would smell it?

"Okay," Steve said cheerfully as they headed toward a hot-dog cart, "how many this time, Buck?"

The vendor's eyes lit up with his excitement when he saw them walking toward him. Last time they'd bought everything he'd had and the guy had been very grateful for the unexpected chance to go home early.

Weirdly, the moment the smell of the hot dogs reached his nose Bucky was ravenously hungry. These days he was pretty used to the way his metabolism worked, but judging by the way his stomach was growling, he hadn't had nearly enough to eat for breakfast. "Just tell the guy to keep serving until I call 'uncle.'"

Steve laughed, clapped him on the shoulder, and then reached for his wallet. Darcy moved into the circle of Bucky's arms as they waited for Steve to get their food organized. Wearing a huge grin the vendor quickly served up a half dozen hot dogs to get them started.

A few moments later Bucky had one in his hand and was lifting it to his lips when the nausea hit him. He turned quickly, retching violently as his empty stomach contracted over and over. The heaving seemed to go on and on, his entire body starting to shake as exhaustion stole through him. He didn't even realize Steve was holding him up until his knees gave way and he didn't actually collapse into a boneless heap on the grass.

He could hear Darcy talking urgently to someone on the phone before the familiar whine of the Iron Man suit's thrusters reached his ears over the sounds of his own gagging.

"Okay, Buckaroo," Tony said through the suit's speakers, "looks like you won yourself a free flight home, princess style."

Bucky wasn't sure what Tony meant by "princess style" but he could probably guess. He just didn't have the energy to protest.

~*~

Darcy barely managed to stay upright as Iron Man lifted her unresisting soulmate into his arms and cradled him close to his chest as if he were a small child. She locked her knees against the panic rioting through her and turned to Steve. He looked as worried a Darcy felt.

"Do you remember your training?" Steve asked.

Darcy blinked, unsure exactly where this conversation was going. Were they under some sort of attack? Was that why Bucky was suddenly so ill?

"Just like we practiced," Steve said, lifting her easily and placing her on his back. Okay, so she was finally getting with the program. They'd practiced this in case Steve or Bucky ever needed to use their super speed to get Darcy out of a dangerous situation. She'd never really enjoyed the sensation, but she was all for clinging to Steve like a barnacle if it meant getting back to the tower and their soulmate that much faster. 

She tightened her grip, closed her eyes, and silently prayed that Bucky would be okay.

~*~

_"Speculation is growing over an unusual incident today in Central Park. The man you can see in this amateur footage has been identified as James Buchannan Barnes, also known as The Winter Soldier. The Avengers have yet to release a statement..."_

Bucky scowled at the TV. The attention probably wouldn't be so bad except for the rather embarrassing fact that five minutes after that video had been recorded he'd felt quite well. Bucky had very literally gone from ravenously hungry, to gagging and retching violently, back to ravenously hungry in the space of less than ten minutes. 

"The PR guys are handling it," Darcy said, easily identifying the reason for his annoyance. She was on the bed beside him, cuddling him the same way he'd cuddled her when she'd been ill a few months ago.

"JARVIS," Bruce said, tilting his head toward the ceiling as if the AI had a physical presence, "before I try to do a blood test"—Bucky was all for avoiding that since extracting blood from the vein of a super soldier was a whole lot harder than it sounded—"are you picking up anything unusual with Bucky's vitals."

"Sargent Barnes's heart rate, blood pressure, and breathing have all returned to normal, though I do detect some sort of echo that I haven't quite been able to identify."

"Echo?" Tony asked sarcastically. "Could you maybe, you know, vague it up a little, J?"

"Apologies," JARVIS said in a tone that didn't sound apologetic at all, "but I'm having trouble narrowing down the source of the sound. If it weren't for Sargent Barnes's super serum I would suspect he had a heart murmur."

"Heart murmur?" Steve asked worriedly. They all knew the version of the serum Bucky had been given wasn't anywhere near as good as the one Erskine had developed for Steve, but there had never been any suggestion that Bucky's body wasn't working at maximum efficiency. And right now he felt perfectly normal. Hungry, but okay.

"Steve," Bruce said, patting his arm reassuringly, "a sound like that is more likely a calibration problem with the equipment."

Tony looked pissed that someone might blame his technology, but he ordered JARVIS to run a diagnostic and then re-evaluate Bucky's results without commenting.

"I'm afraid the results are coming up the same," JARVIS said, this time actually sounding apologetic.

"Can you isolate and play the echo please, JARVIS?"

"Certainly Doctor Banner," JARVIS said politely a moment before a loud, repetitive _whoomping_ sound filled the room. Bruce looked startled. 

"Bruce?" Steve asked worriedly.

Bruce twisted his hands together the way he always did when he was stressed or had been asked a question he didn't particularly want to answer. "Maybe," he said, turning away to open a drawer, "it's time to try some old fashioned medicine."

He grabbed a stethoscope, put the plugs in his ears, and moved toward the bed. He started high up on Bucky's chest, checking his lungs, his heartbeat, and probably a few others things Bucky knew very little about. But it was when Bruce pressed the stethoscope low to Bucky's belly that he really started to worry.

~*~

"Okay," Tony said, gleefully keeping up with Steve and Darcy as they flanked Bucky protectively. He'd insisted on walking down to the medical diagnostics area. "We have a pool going, but since there are really only two possibilities—"

"There are more than two, Tony," Bruce said tiredly.

Tony completely ignored him. "—alien parasite or mutated terrestrial parasite—we're taking bets on size and length instead."

"Tony," Steve growled impatiently. "No betting. Just let Bucky get an ultrasound done so we can figure out exactly what it is and how to treat it."

"Fine," Tony said, acquiescing far too quickly for Darcy's peace of mind. "I'll just go make sure the other Avengers are apprised of the situation."

"Yeah, we can't see through that lie at all," Darcy mumbled as the genius walked away.

"Let him go," Bucky said, tightening his grip on Darcy's hand. "I feel fine, so whatever it is we'll deal with it.

~*~

_A few hours later..._

"A baby?" Steve asked. "A baby parasite?"

"No. A _baby_ baby," the technician repeated, swallowing anxiously. "A normal, healthy, eight-week-old human fetus."

"Inside a man?" Darcy asked. She sounded as bewildered as Bucky felt.

The technician glanced at Bruce, waited for his nod of encouragement, and then turned his nervous attention back to Darcy and Steve.

"Sargent Barnes's ultrasound results are exactly what I would suspect from a healthy, twenty-something woman in the first trimester of pregnancy." 

"Okay, assuming that you're right," Darcy said cutting through the impossible news to try and find an explanation, "how did Bucky get a baby inside him? Last time I checked he didn't have the right parts."

"Well, um," the technician started, his voice cracking on the tiny words, "that's the... that's the part...we um... can't explain."

Bruce nodded and then tilted his head. The technician sighed in relief and then pretty much bolted out the door.

I'm working on some theories," Bruce said flicking through the notes on the tablet in front of him. "Eight weeks ago we fought Doombots twice, dragged a couple of giant mutated crabs back into the ocean, and destroyed that foul-smelling goop monster that Clint somehow exploded with a non-explosive arrow."

"The goop monster," Bucky said in a low growl. "That thing grabbed me, Steve, and Nat before Clint exploded it. Could that have something to do with—" He waved a hand over belly, not really wanting to think of the thing inside him as an actual baby. Even if he was technically pregnant, he was pretty sure he didn't have the right hormones or equipment to maintain a pregnancy.

"We were completely coated by its guts," Steve said. "Stunk even after three runs through the decontamination showers."

"But before it exploded," Bucky said, trying to remember every moment of that very disturbing experience, "the tentacle-like things that latched onto us had seemed to be sucking, almost as if it was trying to feed."

Darcy's arm tightened around him, but she didn't comment.

Steve nodded. "We were all left with red sucker marks on our skin. Bucky and I healed quickly of course, but Nat had the marks for a couple of days."

"Are you sure?" Bruce asked, his curiosity obviously piqued. "If it was extracting DNA it's possible that the process was forcibly reversed when it exploded."

"Meaning what exactly?" Steve asked, tightening the grip he had on Bucky's hand. Thank god he was holding the metal one. Bucky's flesh-and-blood fingers would have been crushed my now otherwise.

"Meaning that..." Bruce wrung his hands together, perhaps realizing that enthusiastic medical curiosity was sort of misplaced right now. "The theories—and they're only theories until we can prove otherwise—are kind of endless at this stage."

"Spit it out, Bruce," Darcy said, clearly annoyed at whatever it was Bruce was trying not to tell them.

"If there was a type of 'backwash' then it's possible the fetus is exclusively Bucky's DNA or a mixture of..." He glanced sideways at Steve. "Or a...um...mixture of others, or... or even partially the goop monster itself."

"So you're telling me I got knocked up by a goop monster?" Bucky asked, trying to control the hysteria rising in his voice.

"It's possible," Bruce said with a small nod, "but everything we know so far indicates that the fetus is human. It's growing and developing at the correct rate for a healthy human pregnancy." 

Bucky guessed that the guy who'd somehow created and managed to contain a giant green rage monster inside him probably knew what he was talking about. 

"So the baby could be a combination of my and Bucky's DNA?" Steve asked, keeping his voice devoid of emotion. Bucky knew the guy well enough to know he was hoping the answer would be "yes."

"Perhaps even Natasha's as well," Bruce said in an apologetic tone. "Everything we know, at this stage, about creating life revolves around the use of an ova harvested from a healthy female."

"So I got knocked up by Natasha?" Bucky asked, trying to break the tension in the room.

"It's possible," Bruce said, avoiding looking at Darcy. "We won't really have any more specific answers unless we take it out and do a DNA test."

"No," Bucky said, surprising himself as much as everyone else in he room. "Let's just...wait and see. Okay?"

Bruce seemed a little bit startled, but Darcy and Steve both nodded. 

"Okay," Steve said, leaning over to press a kiss to Bucky's lips. "We'll just take things one day at a time."

~*~

_Eight weeks later..._

_"Speculation continues regarding the unexpected absence of The Winter Soldier from The Avengers skirmish with Doombots again today. A couple of months ago Sargent Barnes had what The Avengers press release referred to as a 'minor medical episode,' but with his recent nonappearances in The Avengers line up, concerns have once again been raised around the super soldier's health."_

Darcy rubbed a hand over her soulmate's softly rounded belly and couldn't help but laugh at the TV. "I doubt they'd believe the truth."

"I'm not sure _I_ believe the truth," Bucky admitted softly. 

He was now in the second trimester of his pregnancy and according to Bruce and Dr. Cho everything was progressing on schedule. Nothing was guaranteed of course, and Bucky would need to deliver by cesarean before his due date, but both Bruce and Dr. Cho had assured them that it was possible—not guaranteed, but definitely possible—for Bucky to carry the baby to term. His body was adapting quite well to the demands of pregnancy thanks to the super-soldier serum.

"Are you sure you're okay with me keeping it?" Bucky asked softly.

"Of course I am," Darcy said, wondering how on Earth to explain that she wasn't the least little bit upset. 

She'd been shocked at first, of course. When they'd talked about starting a family, she'd kind of assumed she'd be...well... _heavily_ involved, but it had been Natasha's heartbreaking reaction to the news that Bucky's baby was possibly hers as well that had magnified Darcy's already rock-solid resolve to support her soulmates in any way she could. 

Natasha had been forcibly sterilized by the Red Room when she'd been just a child, so she'd never expected to have a child of her own under any circumstances. It had been very clear that she'd wanted to be a part of the kid's life, but she'd immediately offered for her and her soulmates to stay out of their way. Darcy, Bucky, and Steve had made her promise the opposite. This child belonged to all of them, and Natasha, Clint, and Phil should be a big part of the child's life too, no matter whose DNA was involved in the baby's creation.

"I love you so much, Darce," Bucky said, snuggling closer to make room on the sofa for Steve. "Thank you for being so amazing."

Darcy laughed softly and reached over to include Steve in their hug. "Amazing?" she asked. "If I'm the amazing one, then how do we classify you?"

"Our incredible super-soldier baby-mama?" Steve teased.

Darcy giggled. "Or how about," she added, "our astonishing, unbelievable, totally wonderful pregnant sweetheart."

Steve laughed happily. "I like it," he said, lowering his hand to Bucky's belly to join Darcy's. "And I seriously love you both."

Darcy nodded enthusiastically, pressed a kiss to each of her soulmate's lips, and then settled back to watch the rest of the days news on TV.

Yeah, not knowing the child's actual parentage made things a little weird, but that pretty much summed up life with The Avengers. 

Somehow Bucky had been fortunate enough to conceive and so far carry a strong, healthy child. The circumstances didn't matter. DNA didn't matter. The only thing that really mattered was the love they felt for each other, their friends, and the child they'd raise together.

 

THE END


End file.
